Automatic timing advance gear



Jan. 31, 1967 E N CK 3,301,010

AUTOMATIC TIMING ADVANCE GEAR Filed Aug. 24, 1964 INVENTOR.

RALPH R. VERNICK ATTORNEYS United States ?atettt, 6 "ice:

, 3,301,010 AUTOMATIC TIMING ADVANCE GEAR Ralph R. Veruick, Unionville, Ohio 44088 Filed Aug. 24, 1964, Ser. No. 391,367 6 Claims. (Cl. 64-24) The present invention relates to an automatic timing advance gear for, adjusting the timing of the camshaft in internal combustion engines in a manner proportional to engine speed.

Camshafts installed as original equipment in automobiles and the like are normally designed to time the opening of the valves to provide superior engine performance at the relatively low engine speeds encountered in normal city driving conditions. At relatively high engine Speeds, the valve timing remains unchanged, and, as a result, less than maximum performance is achieved at such relatively high engine speeds. In order to improve high speed engine operation, various means have been employed for changing the valve timing, perhaps the most well known of which is the use of the so-called high lift or racing camshafts. The cam surfaces of such racing camshafts are generally formed so as to lift the valves somewhat higher and hold the valves open somewhat longer than camshafts employed as original equipment on automobiles and the like thereby to improve engine performance at relatively high speeds. Although such racing camshafts are satisfactory for the intended purpose, the improved engine performance at high speed is generally offset by poor valve timing at the low speeds encountered in normal driving conditions, characterized by relatively rough idling conditions.

An object of the present invention is to provide an automatic timing advance gear for advancing the rotation of the camshaft proportional to engine speed thereby to vary the valve timing to provide optimum engine performance at all engine speeds.

A more specific object of the present invention is to provide an automatic timing advance gear which can be mechanically or hydraulically operated to automatically angularly adjust the camshaft for optimum valve operation at all ranges of engine speed.

A further object of the present invention is to provide an automatic timing advance gear wherein the hydraulically operated form thereof is conveniently operated by the high pressure oil from the lubrication system of the internal combustion engine.

A further object of the invention is to provide such an automatic advance gear wherein both the mechanically and hydraulically operated forms thereof are simply constructed and economical to manufacture.

Other objects and advantages of the present invention will become apparent as the following description proceeds.

To the accomplishment of the foregoing and related ends, the invention, then, comprises the features hereinafter fully described and particularly pointed out in the claims, the following description and the annexed drawing setting forth in detail certain illustrative embodiments of the invention, these being indicative, however, of but a few of the various ways in which the principle of the invention may be employed.

To id annexed d awing:

FIG. 1 is an end view of the hydraulically operated form of automatic advance gear of the present invention;

FIG. 2 is a sectional view taken on line 2-2 of FIG. 1;

FIG. 3 is a sectional view taken on line 3-3 of FIG. 1;

FIG. 4 is an end view of the mechanically operated form of the automatic advance gear of the present invention, and

3,301,010 Patented Jan. 31, 1967 FIG. 5 is a sectional view taken on line 55 of FIG. 4.

Referring in detail to the drawing, wherein like parts are indicated by like reference numerals, and initiallyto the hydraulically operated form of the automatic advance gear of the present invention as illustrated in FIGS. 13, the camshaft of the internal combustion engine is generally indicated at and is rotatably mounted in front camshaft bearing 12 and sleeve bearing 14. The camshaft is of conventional construction, being of the type installed as standard equipment on automobiles and the like, being formed with cam surface portions (not shown) for sequentially opening the valves which regulate the ilow of fuel into the combustion chamber of the cylinder of the engine in a well-known manner.

The outer end 16 of the camshaft is relatively reduced and is adapted to freely rotatably receive the hub portion 18 of the timing advance gear '20. The latter is retained on the reduced end portion 16 of the camshaft by a gear retainer housing 22, a plurality of mounting bolts commonly designated zit-24 extending through openings provided therefor in the retaining housing into engagement with threaded openings commonly designated at 26 formed in the end of the camshaft. The timing advance gear is adapted to be driven directly from the engine crankshaft through any suitable drive arrangement which has not been illustrated and which forms n part of the present invention.

The front bearing 12 is formed with a passage 28 with the sleeve bearing14 being provided with an opening 30 aligned with such passage whereby high pressure oil from the lubrication pump of the engine is supplied to an annular groove 32 formed in the periphery of the camshaft 10. A transverse passage 34 inter-connects the annular groove 32 with an axial passage 36 formed in the forward end of the camshaft 10. The gear retaining housing 22 is similarly formed with an axial passage 38 which is adapted to be aligned with the axial passage 36 formed in the camshaft when the gear retaining hou ing is operatively mounted to the camshaft whereby the high pressure oil can be delieverd through the described passageways to the gear retaining housing. A sealing ring 40 is seated in an annular opening provided therefor in the gear retaining housing to seal the interface between such housing and the end of the camshaft.

Referring now to the manner in which the camshaft 10 is operatively driven by the timing advance gear 20, the gear retaining housing 22 is formed with radially extending passages 42 and 44 the radially inner ends of which open into the passage 38. The housing 22 is further formed at opposite ends thereof with piston-receiving openings or chambers 46 and 48 of varying diameter which extend transversely to and respectively communicate with the radial passages 42 and 44. Pistons 50 and 52 are adap ed to be movably mounted in the openings 46 and 48, respectively, with the forward ends of such pistons, referring to FIG. 1, being curved and extending outwardly of the openings 46 and 48. The bottoms of the pistons 50 and 52 are exposed to the high pressure lubricating oil entering the bores 46 and 48 through radial passages 42 and 44, respectively.

The timing advance gear 20 is provided with a plu- A return, compression spring 62 is mounted at one end 64 to the gear retaining housing 22 and its other end 66 to shoulder 68 formed on the timing advance gear 20. The spring rate is preselected to return the gear retaining housing 22, and thus the camshaft 10, to a predetermined angular position relative to the timing advance gear 20 to re-establish proper timing following relatively high speed engine operation, as will be presently described.

Referring now to the operation of the FIGS. 1-3 hydraulically operated form of the present invention, the piston 52 is shown therein in a normal or standard timing position, i.e. in a position to maintain the desired angular relationship between the timing advance gear 20 and the camshaft to provide optimum valve operation at the relatively low engine speeds encountered in normal driving conditions. The high pressure fluid from the engine lubrication system flows to the pistons 50 and 52 through the passages 28, 30, 32, 36, 38, and radial passages 42 and 44, respectively. It will be seen that due to the relatively larger area of the bottom of the piston 52, the latter controls the rotative relation between the timing advance gear and the gear retaining housing 22 to which the camshaft 10 is rigidly mounted. In the FIG. 1 position of the piston 52, the return spring 62 is uncompressed.

As the engine speed increases, the engine lubricating oil of the lubricating system correspondingly increases in pressure whereby the pressure acting on the bottoms of the pistons and 52 become relatively greater thereby forcing the piston 52, by virtue of its larger bottom area when compared to the piston 50, outwardly of the piston bore or opening 48 thereby effecting relative rotative movement between the gear retaining housing, and thus the camshaft 10, and the advance timing gear 20. Thus, referring to FIG. 1, the gear retaining housing 22, and thus the camshaft 10, will be rotated slightly counterclockwise, about the axis of the housing and the camshaft, relative to the timing advance gear 20 thereby effectively advancing the position of the chamshaft 10 relative to the position of the same at idling conditions. As the piston 52 is extended outwardly of the gear retaining housing, the piston 50 will be forced to a retracted position and the spring 62 compressed. The piston 50 when moving to such retracted position provides a force opposed to the force acting on the piston 52 thereby providing a dampening effect on the movement of the piston 52 and serving to cushion any bounce from theretur-n spring 62 when the same is compressed. It will thus be seen that the position of the piston 52, and thus the rotative position of the camshaft relative to the timing advance gear 20, is dependent upon the engine speed, transmitted by means of the high pressure lubricating system of the engine. Thus, the greater the engine speed, the higher the pressure of the lubricating oil delivered to the bottom of the piston 52, which results in greater piston travel and resulting angular movement between the camshaft 10 and the timing advance gear 20. In this manner the camshaft 10 is advanced relative to the gear thereby advncing the opening of the engine valves to provide optimum engine performance at the elevated engine speeds. The maximum advance, as will be apparent, is controlled by the piston travel and the rate of the return spring 62.

As the engine speed decreases, the force or pressure acting on the bottom of the piston 52 will similarly decrease to a level whereat the force of the compressed spring 62 will be effective to return the gear retaining housing 22 to its position shown in FIG. 1, in which position the camshaft 10 will be returned to an angular relationship relative to the timing advance gear to provide normal or standard timing for ordinary driving conditions.

Referring now to FIGS. 4 and 5, there is illustrated therein the mechanically operated form of the automatic advance gear of the present invention. In this form of .4 the invention, the camshaft is adapted to be rotated by the timing advance gear 102 through a gearing arrangement comprising a plurality of Weighted gear quadrants commonly designated at 104 and a hub gear 106. The latter is keyed to the camshaft 100 as indicated at 108. The timing advance gear 102 is provided with an annular web portion the radially inner portion of which defines an opening 112 for piloting the timing advance gear on the outer, smooth shoulder of the hub gear 106. The gear quadrants 104 are pivotally mounted relatively adjacent their radially outer limits to the web 110 by means of pivot pins 114 which are preferably press fitted in complemental openings formed in the web 110. The teeth 116 of the gear quadrants 104 meshingly engage the teeth 118 formed on the diametrically enlarged portion 120 of the hub gear 106. As noted above, the hub gear 106 is keyed to the camshaft 100 and it will thus be seen that rotation of the timing advance gear from the crankshaft (not shown) in a conventional manner will be transmitted to the gear quadrants 104 carried by the timing advance gear and thus to the hub gear 106 and camshaft 100 keyed thereto.

The gear quadrants 104 are each provided with laterally oifset curved arm portions commonly designated at 126 which extend into the annular area between the hub gear and the gear drive portion of the timing advance gear. A return spring 128 is provided for each gear quadrant 104, with one end of the spring being secured to a projection 130 formed on the arm 126 relatively adjacent the end thereof, and the opposite end of the return spring being secured to a projection 132 formed on the timing advance gear 102. The return spring rates are preselected so as to properly space the arms 126 and thus the gear quadrants 104 to provide the proper angular relation between the timing advance gear and the camshaft for the relatively low engine speeds encountered in normal city driving conditions. As will be presently described, the return springs are compressed during relatively high engine speeds and function to return the gear quadrants to normal position for low engine speed operation.

A retaining plate 122 is adapted to overlie the gear quadrants 104 to retain the same on the pivot pins 114. The retaining plate 122 is provided with a circular inner opening for piloting the same on the hub gear 106, and is provided with openings arcuately aligned to receive the pins 114 for press fitting the retaining plate in place on the gear hub. It will be apparent that means other than that illustrated could be provided for retaining the plate 122 and thus the gear quadrants 104 in their assembled position. It will be understood that suitable retaining means (not shown) are normally employed for retaining the timing advance gear on the outer end of the hub gear. The retaining plate 122 is provided with openings 134 for receiving the laterally offset ends 126 of the gear quadrants 104 and the return springs 128.

The operation of the FIGS. 45 form is as follows. The rotation of the timing advance gear 102 is transmitted to the camshaft 100 through meshing of the teeth formed on the gear quadrants 104 and the hub gear 106 which is keyed to the camshaft. In normal driving conditions the return springs 128 are uncompressed and serve to maintain the arms 126 and thus the quadrants 104 in the desired angular relation relative to the camshaft to provide optimum valve timing at the lower engine speed encoun tered during normal driving conditions. As the engine speed increases, the rotative speed of the timing advance gear 102 will similarly increase thereby causing the gear quadrants 104, through centrifugal force, to rotate out wardly about their respective pivot pins 114 against the bias of the respective return springs 128. As the gear quadrants are thus rotated outwardly by centrifugal force, the teeth 116 thereof will effect rotation of the hub gear 106 through the gear drive arrangement. Thus, the camshaft 100 is rotated relative to the timing advance gear 102 thereby to advance the timing of the camshaft for optimum valve operation at such higher engine speeds. The degree of relative rotation between the camshaft 100 and the timing advance gear 102 will, as will be apparent, depend upon the attained engine speed and the resistance to compression of the return springs, and the latter will be selected to provide optimum valve operation at all engine speed conditions.

When the engine speed is reduced, the centrifugal force urging the gear quadrants 104 outwardly about their re spective pivotal mountings will gradually diminish until the compressive forces of the return springs 128 overcome the centrifugal force acting on the gear quadrants, at which time the return springs will rotate the gear quadrants about their pivotal mountings to return the quadrants to their predetermined position for relatively low engine speed conditions. The teeth 116 of the gear quadrants 104, through meshing contact with the teeth 118 of the hub gear 166, will thus return the camshaft 106 to its normal setting relative to the timing advance gear 162 to provide optimum valve operation at such reduced engine speeds.

It will be understood by those skilled in the art that engine speed as used herein refers to revolutions per minute (r.p.m.).

It will thus be seen that in both the hydraulically and mechanically operated forms of the invention, the camshaft can be rotated relative to the timing advance gear to vary the valve timing in a manner commensurate with engine speed. Thus, the engine can operate with optimum performance at both low and high engine speeds, which cannot be accomplished with present camshaft constructions, as noted above. Moreover, in both forms of the invention, the arrangement for providing such relative rotation is extremely simple and economical to manufacture, wit-h the hydraulic form being operated by the high pressure oil of the lubrication system of the engine.

Other modes of applying the principle of the invention may be employed, change being made as regards the details described, provided the features stated in any of the following claims or the equivalent of such be employed.

I therefore particularly point out and distinctly claim as my invention:

1. In an internal combustion engine, camshaft means, timing gear means rotatably mounted on said camshaft means, means secured to said camshaft for retaining said timing gear means on said camshaft, means for establishing a drive connection between said camshaft means and said timing gear means comprising piston means mounted in said gear retaining means, said timing gear means when rotating contacting said piston thereby driving said gear retaining means and said camshaft means secured thereto, and means proportional-1y responsive to engine speed for varying the position of said piston thereby varying the angular relation between said camshaft and said timing gear.

2. In an internal combustion engine, camshaft means, timing gear means rotatably mounted on said camshaft means, a gear retaining housing secured to said camshaft for retaining said timing gear means on said camshaft, means for establishing a drive connection between said camshaft means and said timing gear means comprising piston means movably mounted in said gear retaining housing and extending outwardly therefrom, said timing gear means when rotating contacting said piston thereby driving said gear retaining means and said camshaft means secured thereto, means for directing a pressurized fluid to one end of said piston means, the pressure of said fluid being directly proportional to the engine speed thereby varying the position of said piston means and thus the angular relation between said camshaft and said timing gear in a manner proportional to engine speed.

3. The combination of claim 2 wherein said presssurized fluid is conveyed to said piston through passage means formed in said camshaft and said gear retaining housing.

4. The combination of claim 3 wherein the source of said pressurized fluid is the engine lubrication system.

5. In an internal combustion engine, camshaft means, timing gear means rotatably mounted on said camshaft means, a gear retaining housing secured to said camshaft for retaining said timing gear means on said camshaft, means for establishing a drive connection between said camshaft means and said timing gear means comprising piston means movably mounted in said gear retaining housing and extending outwardly therefrom, said timing gear means when rotating contacting said piston thereby driving said gear retaining means and said camshaft means secured thereto, means for directing a pressurized fluid to one end of said piston means, the pressure of said fluid being directly proportional to the engine speed thereby varying the position of said piston means and thus the angular relation between said camshaft and said timing gear in a manner proportional to enigne speed, and spring means operatively disposed between and connected at opposite ends to said gear retaining housing and said timing gear means, said spring means biasing said gear retaining housing and thus said piston to a predetermined position for angularly adjusting the camshaft relative to the timing gear for relatively low speed engine operation, said spring means being compressed at relatively high engine speeds and biasing said gear retaining housing to said predetermined position at the resumption of relatively low speed engine operation.

6. In an internal combustion engine, camshaft means, timing gear means rotatably mounted on said camshaft means, a gear retaining housing secured to said camshaft for retaining said timing gear means on said camshaft, means for establishing a drive connection between said camshaft means and said timing gear means comprising piston means movably mounted in said gear retaining housing and extending outwardly therefrom, said timing gear means when rotating contacting said piston thereby driving said gear retaining means and said camshaft means secured thereto, means for directing a pressurized fluid to one end of said piston means, the pressure of said fluid being directly proportional to the engine speed thereby varying the position of said piston means and thus the angular relation between said camshaft and said timing gear in a manner proportional to engine speed, and second piston means mounted in said gear retaining housing and adapted to engage said timing gear means for dampening the movement of the first recited piston means.

References Cited by the Examiner UNITED STATES PATENTS 517,439 3/1894 Cross 64-26 X 1,257,630 2/1918 Newton 64-25 1,685,839 10/1928 Du Bois 64-26 2,549,748 4/1951 Purdy 64-25 2,653,458 9/1953 Andrews 64-25 2,708,353 5/1955 Brady 64-25 2,950,610 8/1960 Stier 64-24 FOREIGN PATENTS 600,532 7/ 1934 Germany.

FRED C. MA'I'IERN, JR., Primary Examiner,

C. COE, Examiner, 

1. IN AN INTERNAL COMBUSTION ENGINE, CAMSHAFT MEANS, TIMING GEAR MEANS ROTATABLY MOUNTED ON SAID CAMSHAFT MEANS, MEANS SECURED TO SAID CAMSHAFT FOR RETAINING SAID TIMING GEAR MEANS ON SAID CAMSHAFT, MEANS FOR ESTABLISHING A DRIVE CONNECTION BETWEEN SAID CAMSHAFT MEANS AND SAID TIMING GEAR MEANS COMPRISING PISTON MEANS MOUNTED IN SAID GEAR RETAINING MEANS, SAID TIMING GEAR MEANS WHEN ROTATING CONTACTING SAID PISTON THEREBY DRIVING SAID GEAR RETAINING MEANS AND SAID CAMSHAFT MEANS SECURED THERETO, AND MEANS PROPORTIONALLY RESPONSIVE TO ENGINE SPEED FOR 